EP0386822A2 - Processus d'investigation par R.M.N. et appareil pour l'utilisation de ce procédé - Google Patents

Processus d'investigation par R.M.N. et appareil pour l'utilisation de ce procédé Download PDF

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Publication number
EP0386822A2
EP0386822A2 EP90200448A EP90200448A EP0386822A2 EP 0386822 A2 EP0386822 A2 EP 0386822A2 EP 90200448 A EP90200448 A EP 90200448A EP 90200448 A EP90200448 A EP 90200448A EP 0386822 A2 EP0386822 A2 EP 0386822A2
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EP
European Patent Office
Prior art keywords
frequency
pulse
frequency pulse
pulses
selective
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP90200448A
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German (de)
English (en)
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EP0386822A3 (fr
Inventor
Dietrich Joachim Karl Dr. Holz
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Philips Intellectual Property and Standards GmbH
Koninklijke Philips NV
Original Assignee
Philips Patentverwaltung GmbH
Philips Gloeilampenfabrieken NV
Koninklijke Philips Electronics NV
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Publication of EP0386822A2 publication Critical patent/EP0386822A2/fr
Publication of EP0386822A3 publication Critical patent/EP0386822A3/fr
Withdrawn legal-status Critical Current

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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R33/00—Arrangements or instruments for measuring magnetic variables
    • G01R33/20—Arrangements or instruments for measuring magnetic variables involving magnetic resonance
    • G01R33/44—Arrangements or instruments for measuring magnetic variables involving magnetic resonance using nuclear magnetic resonance [NMR]
    • G01R33/48—NMR imaging systems
    • G01R33/483—NMR imaging systems with selection of signals or spectra from particular regions of the volume, e.g. in vivo spectroscopy
    • G01R33/4833—NMR imaging systems with selection of signals or spectra from particular regions of the volume, e.g. in vivo spectroscopy using spatially selective excitation of the volume of interest, e.g. selecting non-orthogonal or inclined slices

Definitions

  • the invention relates to a method for determining the spectral or spatial distribution of the nuclear magnetization in a volume range with the aid of a sequence which comprises at least three slice-selective high-frequency pulses, whereby three mutually perpendicular slices are excited and the nuclear magnetic resonance signal generated in the intersection of these slices is used and an arrangement to carry out this procedure.
  • a method of the type mentioned at the beginning is used for volume selection, i.e. only nuclear magnetic resonance signals from a volume range that are enclosed by a larger volume and are generally located inside a patient are to be processed.
  • the signals from the selected volume range can be used both for spectroscopy and for imaging.
  • a volume range is excited by three high-frequency pulses, which are accompanied by magnetic gradient fields with gradients running in three mutually perpendicular directions.
  • the FID signals occurring in the three excited layers as well as the spin echo signals from the intersections of two layers are dephased by magnetic gradient fields which are effective between or after the three high-frequency pulses. All that remains is a stimulated echo signal that comes from a volume area that corresponds to the intersection of the three layers. In procedures involving stimulated echo signals work, but it is known that only half of the nuclear magnetization excited by the high-frequency pulses is used.
  • the object of the present invention is to specify another method for volume selection.
  • a first solution to this problem provides that the sequence comprises at least four high-frequency pulses, of which the first, third and fourth are layer-selective and each excite three layers, that between the first and third high-frequency pulse - preferably in the middle - a 180 ° high-frequency pulse is provided that phase cycling is carried out with two sequences each and that in these two sequences the phase position of the first or third of the four high-frequency pulses differs by 180 ° or the phase position of the second by 90 °.
  • a second solution to this problem provides that the sequence comprises at least four high-frequency pulses, of which the second, the third and the fourth are slice-selective and excite three slices each, and that the second between the first and the third high-frequency pulse - preferably in the middle - lying high-frequency pulse is a 180 ° pulse.
  • each sequence comprises (at least) four high-frequency pulses, the second of which is a 180 ° pulse, while the other three high-frequency pulses tilt the nuclear magnetization by 90 °.
  • the last two high-frequency pulses are slice-selective pulses that excite two perpendicular layers.
  • the first high-frequency pulse is also slice-selective, i.e. it is accompanied by a magnetic gradient field, the gradient of which is perpendicular to the gradients of the gradient fields accompanying the last two high-frequency pulses.
  • an FID signal or - if a 180 ° pulse follows - is thus obtained from the nuclear magnetization Spin echo signal.
  • the signal components from the areas outside the cutting area can be suppressed by phase cycling by repeating the sequence a second time, the phase position of the first or third high-frequency pulse being changed by 180 ° or that of the second one by 90 °.
  • the nuclear magnetization has a phase position offset by 180 ° in the cutting area, while it does not change its phase position in the areas mentioned outside the cutting area. Subtraction of the signals obtained in the two sequences thus results in a nuclear magnetic resonance signal which is assigned exclusively to the intersection of the three layers.
  • the third layer is selectively excited by the second high-frequency pulse, the 180 ° high-frequency pulse.
  • the second high-frequency pulse the 180 ° high-frequency pulse.
  • the direction of the nuclear magnetization does not coincide with the direction of the stationary homogeneous magnetic field (or the opposite direction), in the presence of which the sequences are carried out, only in the cut region mentioned.
  • the advantage over the first solution is that the volume range is already selected with a sequence, so that phase cycling for volume selection is not necessary. This also eliminates the problems caused by not ideal excitation profile arise within the selected layer. This is offset by the disadvantage that a layer-selective 180 ° high-frequency pulse is required.
  • Both solutions have the advantage over the known method mentioned at the outset that the full nuclear magnetization in the selected volume range can be used for the nuclear magnetic resonance signals and not only half, as in the case of a stimulated echo signal.
  • An embodiment of the invention according to the first or the second solution is characterized in that the non-slice-selective high-frequency pulses are frequency-selective. So the sequence only affects protons of a chemical compound.
  • An arrangement for carrying out the method according to the invention is characterized by a magnet for generating a homogeneous stationary magnetic field, a high-frequency coil for generating high-frequency magnetic fields perpendicular to the direction of the stationary magnetic field, a high-frequency generator for supplying the high-frequency coil with signals whose frequency can be controlled and a plurality of gradient coils Generation of magnetic fields that run in the same direction as the stationary magnetic field and their gradients run in different directions, generators that supply the gradient coils with a current of a predetermined amplitude and a control unit that controls the high-frequency generator and the generators for the gradient coils, that four high-frequency pulses are generated, of which the last two and one of the first two are slice-selective, the second high-frequency pulse being a 180 ° pulse.
  • the 1 contains an arrangement consisting of four coils 1 for generating a homogeneous stationary magnetic field, which can be of the order of a few tenths of a Tesla to a few Tesla. This field runs in the z direction of a Cartesian coordinate system.
  • the coils 1 arranged concentrically to the z-axis can be arranged on a spherical surface 2.
  • the patient 20 to be examined is located inside these coils.
  • each coil 3 is preferably arranged on the same spherical surface. Furthermore, four coils 7 are provided, which generate a magnetic gradient field Gx (ie a magnetic field whose strength changes linearly in one direction) which also runs in the z direction, but whose gradient runs in the x direction.
  • Gx a magnetic gradient field whose strength changes linearly in one direction
  • a magnetic gradient field Gy running in the z direction with a gradient In the y direction four coils 5 are produced, which can be identical to the coils 7, but which are arranged spatially offset from one another by 90 °. Only two of these four coils are shown in FIG. 1.
  • each of the three coil arrangements 3, 5 and 7 for generating the magnetic gradient fields Gz, Gy, Gx is arranged symmetrically to the spherical surface 2, the field strength in the spherical center, which also forms the coordinate origin of the aforementioned Cartesian xyz coordinate system, is only by the stationary homogeneous Magnetic field of the coil assembly 1 determined.
  • a high-frequency, generally frequency- and / or amplitude-modulated, current is supplied to the high-frequency coil from a high-frequency generator during each high-frequency pulse.
  • the high-frequency coil 11 serves to receive the signal emitted by the cores in the examination area. Instead, a separate high-frequency receiving coil can also be used.
  • Fig. 2 shows a simplified block diagram of this magnetic resonance examination device.
  • the high-frequency coil 11 is connected on the one hand to a high-frequency generator 4 and on the other hand to a high-frequency receiver 6 via a switching device 12.
  • the high-frequency generator 4 contains one in its Frequency from a control unit 15 digitally controllable high-frequency oscillator 40, which has vibrations with a frequency in the range of the Larmor frequency of the atomic nuclei to be excited at the field strength generated by the coils 1.
  • the output of the oscillator 40 is connected to an input of a mixer 43.
  • the mixer 43 is supplied with a second input signal from a digital-to-analog converter 44, the input of which is connected to a digital memory 45. Controlled by the control device 15, a sequence of digital data words representing envelope signals is read out of the memory.
  • the mixer 43 processes the input signals supplied to it so that the carrier oscillation modulated with the envelope signal appears at its output.
  • the output signal of the mixer 43 is fed via a switch 46 controlled by the control device 15 to a high-frequency power amplifier 47, the output of which is connected to the switching device 12. This is also controlled by the control device 15.
  • the receiver 6 contains a high-frequency amplifier 60 which is connected to the switching device and to which the signal induced in the high-frequency coil 11 is supplied, the switching device having to have the corresponding switching state.
  • the amplifier 60 has a mute input controlled by the control device 15, via which it can be blocked, so that the gain is practically zero.
  • the output of the amplifier is multiply with the first inputs of two native mixer stages 61 and 62 connected, each delivering an output signal corresponding to the product of their input signals.
  • a signal with the frequency of the oscillator 40 is fed to the second inputs of the mixer stages 61 and 62, a phase shift of 90 ° between these signals at the inputs of the mixer stages. This phase shift is generated with the aid of a 90 ° phase shifter 48, the output of which is connected to the input of the mixer 62 and the input of which is connected to the input of the mixer 61 and to the output of the oscillator 40.
  • the output signals of the mixer 61 and 62 are each fed to an analog-to-digital converter 65 and 66 via low-pass filters 63 and 64, which suppress the frequency supplied by the oscillator 40 and all frequencies above and allow low-frequency components to pass through.
  • This converts the analog signals of the circuit 61..64 forming a quadrature demodulator into digital data words which are fed to a memory 14.
  • the analog-digital converter 65 and 66 and the memory 14 receive their clock pulses from a clock pulse generator 16, which can be blocked or released by the control device 15 via a control line, so that only in a measuring interval defined by the control device that of the high-frequency coil 11, transposed into the low-frequency range, can be converted into a sequence of digital data words and stored in the memory 14.
  • the data words or samples stored in the memory 14 are fed to a computer 17, which uses a discrete Fourier transformation to determine the spectral distribution of the nuclear magnetization and outputs the determined distribution to a suitable display unit, for example a monitor 18.
  • the gradient coil arrangements 3, 5 and 7 are each supplied with a current by current generators 23, 25 and 27, the course of which can be controlled by the control unit 15.
  • a magnetic gradient field Gxa with a gradient running in the x direction is effective, i.e. the generator 27 supplies the gradient coil arrangement 7 with a current with a corresponding time profile.
  • the nuclear magnetization then runs transversely in this layer, while it runs outside the layer in the z direction, i.e. in the direction of the homogeneous stationary magnetic field generated by the coils 1.
  • Fig. 4a indicates the direction of the nuclear magnetization in a x'-y'-z'-coordinate system which rotates at the Larmor frequency and whose z'-axis coincides with the z-axis of the fixed xyz- Coordinate system coincides. It can be seen that the nuclear magnetization is tilted in a vertical direction perpendicular to the plane of the drawing in the y'-direction. On both sides of this layer, the nuclear magnetization is not influenced by the high-frequency pulse HFa, so it remains in the z'-direction.
  • a magnetic gradient field Gx1 is switched on and off.
  • the excited FID signal is dephased by this gradient field.
  • Fig. 4b which shows the nuclear magnetization immediately after this high-frequency pulse, the nuclear spins are tilted outside the layer excited by the first high-frequency pulse in the -z'-direction, while the nuclear magnetization in the previously excited layer within the x'- y′ level remains.
  • phase position of the second pulse in relation to the phase position of the first pulse.
  • phase position is selected so that the nuclear magnetization continues in the y'-direction; however, the invention also works with any other phase position of the second high-frequency pulse.
  • a magnetic gradient field Gx2 is switched on and off after the second high-frequency pulse HFb and before the third high-frequency pulse HFC, in such a way that the time integral above it corresponds to the time integral over Gx1.
  • the nuclear magnetization which is caused by the fact that the 180 ° high-frequency pulse does not tilt the nuclear magnetization by exactly 180 ° everywhere in the examination area, is dephased by Gx2.
  • the third high-frequency pulse HFc is generated, which is designed as a 90 ° high-frequency pulse.
  • This pulse is accompanied by a magnetic gradient field Gyc, so that it influences the nuclear magnetization in a layer perpendicular to the y-axis and the plane of the drawing in FIG. 4c, which indicates the direction of the nuclear magnetization immediately after the third high-frequency pulse HFc, the third high-frequency pulse HFc does not influence the nuclear magnetization in the three upper and the three lower regions; as a result, the direction of the nuclear magnetization is also independent of the phase position of the third high-frequency pulse, i.e.
  • the direction of nuclear magnetization depends in the middle three fields, i.e. in the layer excited by the third high-frequency pulse, from the phase position of the third high-frequency pulse.
  • this high-frequency pulse has the same temporal phase position as the first high-frequency pulse HFa, the nuclear magnetization in the two outer fields of the middle row is tilted by fields in the -y′-direction and in the middle field in the -z′-direction.
  • the third high-frequency pulse HFc is rotated by 180 ° in phase instead, the nuclear magnetization points in the two outer fields in the + y′-direction and in the middle field in the + z′-direction.
  • FIG. C by the fact that the direction of the nuclear magnetization for the first case and in the lower part of the field for the second case are indicated in the upper part of each field. The same can be achieved by a 90 ° phase change of HFb.
  • a magnetic gradient field Gx3 is switched on and off, the gradient of which extends in the x direction, but can also run in the y or z direction. This will remove all of the transverse magnetization generated by the previous radio frequency pulses, i.e. the magnetization that does not point in the + z or -z ′ direction dephases in particular the FID generated by HFc. As a result, the four middle fields of the upper and lower rows or of the left and right columns can no longer make any contribution to a nuclear magnetic resonance signal which is generated later.
  • a fourth high-frequency pulse HFd is generated.
  • the fourth high-frequency pulse HFd is a slice-selective 90 ° pulse, which is accompanied by a magnetic gradient field Gzd with a gradient running in the z direction. This excites a layer perpendicular to the z-axis, which contains the plane of the drawing in FIG. 4. Only in this layer is the nuclear magnetization tilted by the 90 ° high-frequency pulse. Depending on whether the nuclear magnetization in the field in question was previously directed in -z ′ or in + z ′ direction, this pulse folds the nuclear magnetization in the direction -y ′ or y ′.
  • the five fields of the layer identified in this way thus provide an FID signal through free induction decay or, in conjunction with a subsequent 180 ° high-frequency pulse, a spin echo signal. These can be used for spectroscopy or imaging.
  • the direction of the nuclear magnetization in the central field depends on the phase position of the first three high-frequency pulses While the orientation of the nuclear magnetization in the four corner fields is not affected by this, it is possible to carry out phase cycling in which the influence of the components of the nuclear magnetic resonance signal originating from the square fields is eliminated.
  • the sequence shown in FIG. 3 is repeated once more, only the phase position of the third (or the first) high-frequency pulse being rotated by 180 ° or that of the second by 90 °. If, for example, the third high-frequency pulse in the first sequence has the same phase position as the first high-frequency pulse, then in the second sequence the third high-frequency pulse has the opposite phase position as the first.
  • the components of the nuclear magnetic resonance signal originating from the nuclear magnetization in the four corner fields then have the same phase position as in the first sequence, while the signal component originating from the central field has the opposite phase position.
  • the influence of the signal components originating from the corner fields can therefore be eliminated, so that the resulting difference signal only contains signal components which are separated from the nuclear magnetization in the central field, which is the intersection of the three slice-selective high-frequency pulses HFa, HFc and HFd corresponds to excited layers.
  • the full nuclear magnetization is used in each sequence, which results in a better signal-to-noise ratio compared to the STEVE method.
  • the Phase coding made a magnetic gradient field Gy1 effective, the time integral of which is changed step by step after every two sequences (in which the phase position of, for example, the third high-frequency pulse differs by 180 ° with respect to the first).
  • a magnetic gradient field Gx5 running in the x direction is switched on, which is selected such that the time integral over this field is just as large as the time integral over the maximum of the spin echo signal the magnetic gradient field Gx4.
  • FIG. 5 shows an exemplary embodiment of a sequence which makes it possible to directly obtain an FID signal (or a spin echo signal) from the intersection of three layers excited by high-frequency pulses.
  • This sequence like that of FIG. 3, has four high-frequency pulses, of which the second (HFb) in turn is a 180 ° high-frequency pulse, while the other three can be 90 ° pulses.
  • the third and fourth high-frequency pulses HFc and HFd are in turn designed as slice-selective high-frequency pulses, which are accompanied by a magnetic gradient field Gyc and Gzd.
  • the first high-frequency pulse HFa is not slice-selective, i.e. it is not accompanied by a magnetic gradient field
  • the 180 ° pulse HFb is accompanied by a magnetic gradient field Gxb.
  • FIG. 6 shows the direction of the nuclear magnetization after each of the highs represents frequency impulses in nine fields within a layer perpendicular to the x-axis.
  • the nuclear magnetization is tilted by 90 ° in the entire examination area. It then runs, for example, in the direction y '.
  • the time integrals over the magnetic gradient fields Gx1 and Gx2, which are effective before and after HFb, must be the same and the gradient Gxb is chosen so that its time integrals before and after t1 are the same. It is thereby achieved that transverse magnetization outside the layer selected by HFb and Gxb, which lies in the intermediate plane of FIG.
  • the third high-frequency pulse influences the nuclear magnetization in a layer perpendicular to the plane of the drawing, which contains the middle column of fields. Its phase position is either the same as that of the first high-frequency pulse or it is offset by 180 ° with respect to this. As a result, the nuclear magnetization in the three fields of the middle column is tilted either in the -z'-direction or in the + z'-direction, depending on the phase position, while it remains unchanged in the two outer columns.
  • the magnetic gradient field Gx2 effective between the third high-frequency pulse HFc and the fourth high-frequency pulse HFd dephases the transverse nuclear magnetization in the areas on both sides of the layer excited by the second high-frequency pulse HFb (above and below the plane of the drawing) and in the six fields of the two outer field columns.
  • the nuclear magnetization pointing in the + z or -z ′ direction remains only within the three fields of the middle column.
  • the fourth high-frequency pulse HFd acts on a layer perpendicular to the z-axis, which is horizontal and perpendicular to the plane of the drawing and which includes the middle of the three fields in the middle column, the central field. Only in this central field can the fourth high-frequency pulse cause transverse magnetization, since in the remaining areas of the layer the nuclear magnetization was rotated by the third high-frequency pulse HF 3 in the z'-direction. As a result, a nuclear magnetic resonance signal is available after the fourth high-frequency pulse HFd, which is exclusively determined by the nuclear magnetization in the intersection of the three layers excited by the high-frequency pulses HFb to HFd.
  • a spin (echo) signal can again be generated by means of a further (non-selective) 180 ° high-frequency pulse, but the FID signal which is generated by the fourth high-frequency pulse can be used directly.
  • the nuclear magnetic resonance signal obtained both for imaging and for spectroscopy is detected and subjected to a Fourier transformation - preferably after the sequence has been repeated enough times and the nuclear magnetic resonance signals have been summed.
  • a frequency-selective high-frequency pulse (binomial pulse, DANTE pulse) before the first and / or the fourth high-frequency pulse of the sequence according to FIGS. 3 and 5, which only excites this nuclear magnetization, which is dephased by a subsequent magnetic gradient field, so that they won after the fourth high frequency pulse makes no contribution to the nuclear magnetic resonance sign.
  • the HF pulse HFb in sequence Fig. 3 or HFa in sequence Fig. 5 can be made frequency-selective so that it only acts on protons of a chemical compound (eg fat). Other components are dephased and no longer contribute to the NMR signal.
  • the fourth high-frequency pulse HFd is a 90 ° pulse. If you replace this fourth high-frequency pulse with a sequence of small-angle pulses with subsequent phase coding, then a quick mapping of the selected volume range is possible. Small-angle pulses are to be understood as high-frequency pulses that tilt the nuclear magnetization by an angle from the z direction that is small in comparison to 90 °, for example 10 °.
  • the 180 ° high-frequency pulse HFb is located exactly in the middle between the first high-frequency pulse HFa and the third high-frequency pulse HFC. If HFb is not exactly in the middle, the methods will still work, but the signal-to-noise ratio will be worse.

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  • Physics & Mathematics (AREA)
  • Optics & Photonics (AREA)
  • Spectroscopy & Molecular Physics (AREA)
  • High Energy & Nuclear Physics (AREA)
  • Condensed Matter Physics & Semiconductors (AREA)
  • General Physics & Mathematics (AREA)
  • Magnetic Resonance Imaging Apparatus (AREA)
EP19900200448 1989-03-04 1990-02-26 Processus d'investigation par R.M.N. et appareil pour l'utilisation de ce procédé Withdrawn EP0386822A3 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE3906979A DE3906979A1 (de) 1989-03-04 1989-03-04 Kernspinuntersuchungsverfahren und anordnung zur durchfuehrung des verfahrens
DE3906979 1989-03-04

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EP0386822A2 true EP0386822A2 (fr) 1990-09-12
EP0386822A3 EP0386822A3 (fr) 1991-03-13

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EP19900200448 Withdrawn EP0386822A3 (fr) 1989-03-04 1990-02-26 Processus d'investigation par R.M.N. et appareil pour l'utilisation de ce procédé

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EP (1) EP0386822A3 (fr)
JP (1) JPH0316553A (fr)
DE (1) DE3906979A1 (fr)
IL (1) IL93611A0 (fr)

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE4402646C1 (de) * 1994-01-29 1995-06-22 Bruker Medizintech Magnetresonanzmessung mit geschaltetem Phasenkodiergradienten
JPH07257307A (ja) 1994-03-22 1995-10-09 Nippondenso Co Ltd 車両用エアバッグ装置

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0278254A1 (fr) * 1987-01-30 1988-08-17 Siemens Aktiengesellschaft Appareil pour déterminer des spectres de résonance magnétique nucleaire dans des régions spatialement choisies d'un objet examiné
EP0304984A1 (fr) * 1987-08-12 1989-03-01 Koninklijke Philips Electronics N.V. Analyse spectrale avec sélection de volume utilisant des échos refocalisés
EP0329240A2 (fr) * 1988-02-17 1989-08-23 Philips Patentverwaltung GmbH Procédé pour déterminer la distribution spectrale de la magnétisation nucléaire dans un volume limité et dispositif pour la mise en oeuvre du procédé
EP0347990A1 (fr) * 1988-06-22 1989-12-27 Koninklijke Philips Electronics N.V. Procédé et dispositif de détermination d'un spectre RMN au moyen d'impulsions sélectives de transmission de polarisation

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0278254A1 (fr) * 1987-01-30 1988-08-17 Siemens Aktiengesellschaft Appareil pour déterminer des spectres de résonance magnétique nucleaire dans des régions spatialement choisies d'un objet examiné
EP0304984A1 (fr) * 1987-08-12 1989-03-01 Koninklijke Philips Electronics N.V. Analyse spectrale avec sélection de volume utilisant des échos refocalisés
EP0329240A2 (fr) * 1988-02-17 1989-08-23 Philips Patentverwaltung GmbH Procédé pour déterminer la distribution spectrale de la magnétisation nucléaire dans un volume limité et dispositif pour la mise en oeuvre du procédé
EP0347990A1 (fr) * 1988-06-22 1989-12-27 Koninklijke Philips Electronics N.V. Procédé et dispositif de détermination d'un spectre RMN au moyen d'impulsions sélectives de transmission de polarisation

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
MAGNETIC RESONANCE IN MEDICINE. vol. 6, no. 1, Januar 1988, DULUTH,MN US Seiten 107 - 115; G. JOHNSON ET AL.: "Multiline Chemical-Shift <MULCH> Imaging" *

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JPH0316553A (ja) 1991-01-24
EP0386822A3 (fr) 1991-03-13
DE3906979A1 (de) 1990-09-06
IL93611A0 (en) 1990-12-23

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